A Prospective Study of Multivitamin Supplement Use and Risk of Breast Cancer

Abstract and Introduction

The authors evaluated the association between multivitamin supplement use and breast cancer risk in a completed trial. At baseline (1992–1995), 37,920 US women aged ≥45 years and free of cancer provided detailed information on multivitamin supplement use. During an average of 10 years of follow-up, 1,171 cases of invasive breast cancer were documented. Multivitamin use was not significantly associated with overall risk of breast cancer. Compared with the risk for never users, the multivariable relative risks were 0.97 (95% confidence interval: 0.81, 1.16) for past users and 0.99 (95% confidence interval: 0.82, 1.19) for current users. Current multivitamin use for ≥20 years or ≥6 times/week was also not significantly associated with risk. Multivitamin use was nonsignificantly inversely associated with risk of breast cancer among women consuming ≥10 g/day of alcohol and with risk of estrogen receptor negative–progesterone receptor negative breast cancer. Multivitamin use was nonsignificantly associated with a reduced risk of developing ≤2-cm breast tumors but an increased risk of >2-cm tumors. The authors' data indicate no overall association between multivitamin use and breast cancer risk but suggest that multivitamin use might reduce risk for women consuming alcohol or decrease risk of estrogen receptor negative–progesterone receptor negative breast cancer.

Multivitamin supplements are the most commonly used dietary supplements in the United States. According to the 1999–2000 National Health and Nutrition Examination Survey, 35 percent of adults reported recent use of multivitamin supplements.[1] Numerous experimental studies have suggested some favorable effects of several individual vitamins contained in multivitamin supplements on DNA synthesis and repair, DNA methylation, oxidative damage, inflammation, angiogenesis, immunity, cell differentiation, cell proliferation, and apoptosis.[2,3,4,5,6]

Most epidemiologic studies on vitamins and breast cancer risk to date have focused on individual vitamins.[7,8,9] Three previous prospective cohort studies have evaluated the association between multivitamin supplement use and risk of breast cancer; one reported an inverse association among those who regularly consumed alcohol,[10] but two others found no overall association.[11,12] Because of limited data on multivitamin supplement use and breast cancer risk, we conducted a detailed analysis in the Women's Health Study, a large prospective cohort.

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Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.